assume cs:codesg

codesg segment
	start: mov ax,2000H
	       mov ds,ax
	       mov bx,0
	s:  mov cl,[bx]
	    mov ch,0
		jcxz ok
		inc bx
	    jmp short s
	ok: mov dx,bx
	    mov ax,4c00h
		int 21h
codesg ends

end start